High-frequency terminal



latented l5,

2,603,711 HIGH-FREQUENCY TERMINAL John R. -Woodyard, Berkeley, Calif., assignor to The Sperry Corporation, Great Neck, N. Y., a corporation of Delaware Application December 14, 1946, Serial No. 716,210

4 Claims.

The present invention relates generally to ultra. high frequency vacuum tube structure and, more specifically, to vacuously sealed high frequency lead-insfor such tubes. The invention is illustrated as applied to ultra high frequency elec-- 'tron discharge devices utilizing hollow or cavity resonators and, more particularly, to terminal posts or high frequency couplings to or from such resonators. The present application is a continuation-in-part of copending application Serial No. 428,682, for High Frequency Tube Structure, filed January 29, 1942, now Patent No. 2,414,785.

In ultra high frequency electron discharge devices using cavity resonators, it has become usual practice to utilize the walls of the cavity resonator as part of the vacuum envelope for the device. To couple ultra high frequency energy to or from these devices, it has also been known to utilize coaxial line couplings or terminal posts having an outer conductor communicating with the resonator cavity through an opening in the wallthereof and having an inner conductor connected to the outer conductor by a coupling loop at the end thereof which is positioned within the space enclosed by the resonator and which accordingly'couples the output line to the electromagnetic field within the resonator. To maintain the evacuated condition of the resonator and of the device, it has become usual to provide a vitreous vacuum seal between the inner and outer conductors of this coaxial line terminal post. Structure of this type, for example, is shown in Fig. '7 of Hansen et al. Patent No. 2,311,658, issued February 23, 1943.

In the past, trouble has been experienced in many instances with this seal between the inner and outer conductors of the coaxial line terminal post. For connection of the electron discharge device to other circuits, it'isnecessary, of course, to couple suitable concentric lines or other high frequency conductors to the terminal posts of the discharge device. When such couplings are not accurately formed or when the seal from the terminal post is not accurately made, misalignment between the inner conductor of the terminal post and the inner conductor of the connecting line causes strains to be transmitted to the seal, which is usually in the form of a glassbead. Such strains, if severe enough or repeated often enough, frequently result in breaking the seal, with resultant loss in vacuum. Also, the normal handling of such devices may cause the inner conductor of the terminal post to accident'ally come into contact with other objects.

The shock of such impact frequently cracks the seal and renders the device useless.

According to the present invention, provision is made to render such device and seals more rugged, both for ordinary handling and for connection to other circuits. For this purpose an enclosing sleeve is placed about the terminal post to prevent the tip of the inner conductor from being exposed and susceptible to impact with external objects. Also, to minimize the eifect of such impact, the inner conductor of the terminal post is formed with a section of restricted cross-sectional area which may readily bend. Such bending will occur to absorb the shock of impact with an external object or to absorb the effect of misalignment with the lines coupled to the terminal post and will prevent strains from being transmitted to the seal. In this manner a highly rugged high frequency lead-in and seal, useful in coaxial or concentric line terminal posts, are provided, and the breakage formerly encountered has been substantially minimized.

Accordingly, it is an object of the present invention to provide novel high frequency lead-ins and seals afiording improved ruggedness for use with tube structures.

It is another object of the present invention to provide improved concentric or coaxial line terminal post means for ultra-high-frequency evacuated cavity resonators.

It is another object of the present invention to provide improved concentric line terminal posts for evacuated cavity resonators, and provided with means for preventing damage to the seal thereof due to physical impact.

Other objects and advantages of this invention will become apparent from the specification, taken in connection with the accompanying drawings wherein the invention is embodied in concrete form.

In the drawing,

Fig. 1 is an elevational view, partly in crosssection, of an electron discharge device embodying the improved high frequency lead-in and seal of the present invention.

Fig. 2 is an enlarged sectional view of the high frequency lead-in and seal.

The present invention is illustrated as used in a single-resonator electron beam velocity-modulating tube structure of the reflex type as disclosed in Fig. 2 of vPatent No. 2,250,511 for Oscillator Stabilization System, granted July 29, 1941 to Russell H. Varian and William W. Hansen.

Referring to the drawing, the cathode structure of this tube consists of emitter surface I which may be of the oxide-coated type heated by a resistance heater 2, emitter I being coaxial with and surrounded by a focusing shield 3 which is illustrated as containing a woven mesh grid 4 that may act as a control or modulator grid as desired. Electrons from emitter I are projected in a beam of round cross-section through an accelerating andfield-smoothing grid 5 by means of any' suitable unidirectional voltage (not shown) applied between cathode I and a plate 6. Plate 6 is provided with a cylindrical neck portion I in which grid 5 is mounted and which serves to provide a field-free space inwhich the electron beam travels toward .andthrough entrance grid 8 of a hollow conducting. resonator ofv resonator 9. An inner rod 24 concentric with tube 23 serves as the inner conductor of the terminal post. It may be of tungsten and is position coaxially of tube 23 by a glass vacuumtight seal or insulating plug 25. The inner end 26 of rod 24 supports one end of coupling loop 21 electrically integral therewith, the other end of loop 2! being welded ,tothe inner end of tube 23. The outer end of inner'condu'ctorid is conical, as shown at 50, to facilitate fitting of the inner conductor of a concentric line to be at- .tached thereto, which is usually formed with a recess cooperating with tip 50.

9. Resonator 9, as shown, has a reentrant portion Ill, a flexible end wall I I, an outer cylindrical wall I2, and rigid flat end 'wall I3 oppbsit wall II. End wall I3 of resonator 9 is apertured and carries a grid structure I4 concentric with and o e togrid ll. ,Grids'a .8 and L may have an desired form. as sho n. in o ab vmment qned ar a pli ati n N 2 82, QQW Patent. N .4 ,4 S ed c n ent t arid 5 andcl s behind it is a reflector electrode I8 which may be s -s d ssh wnfl ct r 1. s su ported by conductor I9 which passes through lass nd l w i h i u p ted, b n S a e t end W l 1 9i so a r in th denventional manner.

n operation, the e e ron b am emitte from cathode I is projected through accelerating and smoothing grid 5 and through entrance grid 3 into resonator 9. in this resonator Q the beam sufiers recurrent velocity changes or is velocity modulated by an oscillating electric fieldexisting between grids 8 and l The .bam tra els ou through exit grid and is reflected back through grid I4 by a potential applied to reflector I8 approximately equal to that of the: cathode I. The reentry of the beam into resqnator 9 takes place after recu1-rentbunching or density modulation of the'be'amhastaken place. The grouped beam then givesup energy to thealternating electric field between grids I4 3, thus maintaining oscillations in resonators. I

End plate 6 and end wall I3 are: provided with flange extensions 30"and 29, respectively, which extend perpendicularly'to the axisof the tube. Flange 29 is provided with three'screw's 3'] which may be spaced 120 apart near the'periphery of this flange 29, having slotted ends facing away from flange 30. Screws SI'are'providedon their inner ends with socket 'join'ts 38. for receiving the ends of cylindrical struts. 39', which struts have hemispherical ends 40 bearing msdcktsm in flange 30. Struts 39 are forced to beari'with the proper force against flange 30 by'sp'rin'gs 42 which are under tension between flanges 2 9"a'n d 30 and may be spaced 120 apart'near the be; ripheries of these flanges intermediatethe screws 31. Rotation of screws 31 varies. the. distance between grids 8 and I4, thereby'changingthe natural frequency of resonator 9" and theoi tput frequency of the device.

Resonator 9 is provided with coaxial line terminal posts or elements 2] and 22jemerging from resonator end wall I3. These term irialpos ts include a tube or'tubular'portionfi which may be of Kcvar an alloy of approximately nickel, cobalt and 55% iron described. in Patent No. 1,942,290 or other metal readily seal able to glass and forming th out'er con'ductor of the concentric line terminal post. "rate 23 I of said loop said is soldered or brazed into an aperture in wall I3 7 Slightly above the outer surface of glass seal 25, rod 24 has a. relieved or constricted section 28'. 'It is found that without the small diameter section 28, if the outer end 50 of rod 24 is accidentally hit, glass seal 25 would break near rod 24. However, with the constricted section 28, this section merely bends if accidentally hit, and the seal 25 is not broken. To minimize ,t f l'iae es u a q ii i f 's k n ducting tube 23 is surrounded by a Q0 a1. 21 which extends above the insulating seams aiid around unto; Collar12l also 'is" attached to ,t be 23' adjacent seal 25 and serves to reenrercetuae Concentric line terminal posts such as, 2| and 22 may'also be massa e that they project r' rally from the cylindrical wall "I2, lie i rather than from end wall I3 of the reso'na The present invention thus provides ate high frequency lead-in for vacuum tubes" which is rugged and stands up well under wideiylvary ing conditions of use. This leadin i'sfc'spec ly useful for high power leads, since'it is 12; to use the large diameter conductors page 3; to prevent heating at the seal which might'ini pair its effectiveness, while at'the same time making it possible, tQ minimize t l. Shock s usnecessarily rigid lead-ins; Since many changes could ,be made; in the above construction and many apparently widely diifferent embodiments of this invention be made without departing from the sec til" of, it is intended that all matter cdntai edln the above description or. shown in the] gf panying drawingsfs hall be interpreted a, ill, trative and not in a limiting sense] What is claimed is:' w A ncentri l n t r n hqst o h llow r nate m sin e t to .ctin tuh adapted to have its inne'rportion'pr acting the apertured wall of a hollow resori outer portion of said tube having are o a ther on a onduc or. e i tr 'wi hin sa ou ertube'. a L lhav a 99 n s t nbetw n tann r a we S utgrf be or ro ecting int 1. -inte weete for o in with'th f i dt tee; i gg isl al e w en a inn r-.- pli u. "f; ai oute con u t n i lmsitiqns Y a I inner conductor i benda le po tion o twardly of. sex outer end of said reinforcing cellar a inner conductor terniinating common plane. q 2., A concentric, line terminal-post for hollow resonators comprising ,an' outer: cpnduetin i M joined to the wall of a hollow reso ifia Q communicating with the 'iiite or he e outer portion of saidtube 1i collar thereon' aninne'r con tor @ii nt nrreinstati g.t na ha 5 a coupling connection for coupling with the high frequency energy Within said resonator, a vitreous seal between said inner conductor and said outer conductor, said inner conductor having a constricted portion outwardly of said seal and within said reinforcing collar whereby unexpected forces applied to said terminal post are prevented by said collar from injuring said seal, said constricted portion also aiding in the protection of said seal by enabling the ready bending of said inner conductor under stress.

3. A coaxial line seal comprising a conductive tubular portion, a conductive rod extending therethrough, a reenforoing collar around a part of the tubular portion, and an insulative plug within the part of the tube surrounded by the collar, said plug being sealed to both the tubular portion and to the rod.

4. A concentric line terminal post comprising an outer conducting tube, an inner conductor positioned concentrically within said outer tube, an insulating seal between said inner conductor and said outer tube and supporting said inner conductor relative to said outer tube and sealing the inward portion of the interior of said outer tube from the outward portion thereof, said tube having a reinforcing collar surrounding said seal and extending outwardly thereof and overlying the free end portion of said inner conductor, whereby shocks applied to said terminal post will be prevented from appreciably jarring said inner conductor thereby protecting said seal against fracture.

JOHN R. WOODYARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,085,074 Boyles June 29, 1937 2,311,658 Hansen Feb. 23, 1943 2,394,398 Mouromtseif Feb. 5, 1946 

